1. Field of the Invention
This invention relates to an assembly of extendable, or projectable, and retractable spikes for use with footwear. More specifically, in the working embodiment, an array or assembly of ground-engaging spikes is encased in the sole-heel matrix of a piece of footwear and mechanized so that the spikes may be projected from the sole-heel in a surface-contacting protrusion or retracted when their gripping facility is no longer desired.
2. Discussion of the Relevant Art
Structures similar to that described above are known in the art. The concept of a projectable and retractable anti-slip device is employed in the shoe or boot footwear associated with hiking and skiing, and could be conceivable employed in other sports such as golf. In my search for relevant art, I discovered several patents which taught purely mechanical actuation devices for projectable and retractable spikes. U.S. Pat. No. 3,793,751 discloses a retractable spike apparatus for use in a golf shoe and the like. By turning a knob which projects or protrudes from the heel of the shoe, two eccentrically mounted shafts, that are coupled by a flexible, intermediate shaft, effect a camming action that forces each of two strap-captured plates downward. The plates carry a plurality of spikes which are caused to protrude through the heel-sole portion of the shoe into ground contact. Further rotation of the camming shafts causes their retreat from the plates, allowing them to be rebiased in the upward position and withdrawn into the sole-heel ensemble. A ski boot traction device, disclosed in U.S. Pat. No. 3,717,238, teaches a retractable anti-slip spike assembly encased in a ski shoe and consisting of a tubular metal casing transversely embedded in the sole and the heel of the shoe. The casing has a longitudinally rotatable camming member mounted over a longitudinal plate element that is provided with a plurality of depending spikes which are accessible through openings in the bottom wall portion of the shoe casing. The plate member is spring-biased upwardly in order to retract the spikes while the rotatable camming member may be manually operated through use of a radial handle element which is accessible to the user. As with '751, this device utilizes at least one camming member to drive the spikes downward through a plurality of openings in the sole-heel of the boot. Still employing a camming action, but using a spike array that need not be afforded openings in the sole-heel ensemble, U.S. Pat. No. 4,375,729, for footwear having retractable spikes, employs a mechanism for selectively extending and retracting the spikes through the use of finger pressure on an enclosed heel cam extension bar. By digital manipulation, a heel locking mechanism is released and a rigid cam member is moved to a forward or rearward direction. The spikes are mounted on a resilient plate in a retracted position and the plate is superimposed by the cam member. As the cam member slides over the spike plate, individual cam portions of the upper member slide over the spike bases and push them downward, causing them to extend beneath the sole-heel plane. A great advantage of the '729 device is that the spike driving mechanism is relatively inaccessible through the base of the shoe or boot which encases the entire spike assembly.
German Patent No. 191178, issued in 1907 discloses an early attempt to translate a longitudinally disposed gang-bar by means of an articulated knuckle which is rotated by a key mechanism. Most interesting is the use of a metal framework for mounting thereon the pivotation axis of several cleats. This device was readily amenable to strap-on (the shoe) usage and in the northern United States and Canada was commonly referred to as an "ice creeper" or "ice walker". The articulated portion is restricted only to the knuckle mechanism, the gang-bars of the disclosure consisting only of fairly rigid ribbonous shafts. Straps for donning the creepers are affixed, as with all devices of this type, near heel and mid-sole portions of the frame. State-of-the art patent, U.S. Pat. No. 5,337,494 discloses a cleated shoe mechanism that is actuated to move spikes into and out of a plurality of "pits" located in the bottom of the sole. This mechanism is housed or encased in the sole-heel portion of a shoe and thus, the pits are a useful adjunct to my invention.
Finally, the Brookstone (Reg. TM) Catalog of Hard To Find Tools (Brookstone T-1-95A1; Mexico, Missouri--Copyright 1994) features a cover advertisement for strap-on "ice walkers" that are useable with low-heel dress shoes. It is clear that the removable facility is contemplated with such "strap-ons" because of nonretractability of the cleats.
In order to provide a noteworthy advancement in this field, I have devised an extensible and retractable shoe spike assembly, the spikes of which are extensible from and retractable into pits located in the firm, cast portions of the sole and heel, that is the base, of a shoe or boot. Minimizing apertures in these portions of the footwear obviates a degradation of the mechanism due to fouling by the entrance into the extension-retraction mechanism of soil, mud or other debris. On the other hand, the simple and elegant mechanization of '751 could not be ignored, nor could the fact that is it operated without the use of tools and can be readily manipulated by a youngster or a person's gloved hand. Very little technique is required in a simple rotation of a knob.
3. Incorporation by Reference
Because they disclose first of their kind mechanisms or state-of-the art, the patents U.S. Pat. No. 5,337,494 and German No. 191178 are incorporated by reference. To the extent that is discloses strap-on walking cleats, the Brookstone (Reg. TM) Catalog is also incorporated by reference.